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700r4 swap into a M1008

captw

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Bailieboro, Ontario, Canada
700R4 swap

it makes no sense to install the 700R4 into an otherwise unmodified M1009, unless you leave the transmission selector in drive, and don't use OD, because the axle ratio is 3:08 to 1....the engines in these trucks were designed to run at a decent RPM, but with the 700R4 and 3:08 gears it will be very lazy at highway speed....the only useful thing with this combo is that if wired up, the lockup in the TC will give you better fuel economy in "Drive"....these aren't idle statements, I own a 1985 C10 longbed that came out of the factory with 6.2L, 700R4, 3:08 gears....the OD is only useful once the truck is approaching 75 MPH.....the M1008 is a candidate for the this swap, due to the 4:56 gears, providing the 700R4 is strengthened if you want to use the truck in a harsh environment...in the end it's left to the vehicle owner to decide what to do, but if you have a M1009, it may be alot of effort and expense for nothing other than a lock up converter giving you a little better fuel economy....W
 

WARWAG

Active member
it makes no sense to install the 700R4 into an otherwise unmodified M1009, unless you leave the transmission selector in drive, and don't use OD, because the axle ratio is 3:08 to 1....the engines in these trucks were designed to run at a decent RPM, but with the 700R4 and 3:08 gears it will be very lazy at highway speed....the only useful thing with this combo is that if wired up, the lockup in the TC will give you better fuel economy in "Drive"....these aren't idle statements, I own a 1985 C10 longbed that came out of the factory with 6.2L, 700R4, 3:08 gears....the OD is only useful once the truck is approaching 75 MPH.....the M1008 is a candidate for the this swap, due to the 4:56 gears, providing the 700R4 is strengthened if you want to use the truck in a harsh environment...in the end it's left to the vehicle owner to decide what to do, but if you have a M1009, it may be alot of effort and expense for nothing other than a lock up converter giving you a little better fuel economy....W


The title says http://www.steelsoldiers.com/cucv/7464-700r4-swap-into-m1008-3.html#post838138 . If it was a typo and intended for a M1009 I would not see a reason to do this swap as stated above. BUT if for a M1008 then I stand by what I said.[thumbzup]
 

seabee mike

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Fallon NV
look on cracklist, I see 700r4 on there for $100-200 all day long. There cheap to build up also, with a few simple upgrades they can handle 300-400 H.P. I just got 2 of them for free will be installing them in mine.
Do I need to re gear them? or are they all geared the same?
 

southdave

Active member
1,986
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ripley, oh/TDY Lordstown,Oh
Sort of, you have good point on which to build
you need a B29 torque converter
T V cable and bracket- jurys out wheather or not a universal will work..
maybe a diesel governer spring although I have read that one for 305 is close enough to work well..
you will need a flex plate as well
 

FLINT

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Western VA mtns.
Ok, I think I understand now - it would be better if the donor parts came from a diesel truck - that way it would have all of the appropriate pieces.
 

WARWAG

Active member
You will also need a TH350 adaptor to mount onto the back of the 700R4 that will mate to the NP208. Both the 27 spline output shaft and Th350 adaptor can be had at Advance Adaptors. IF your having the transmission built for you order the 27 spline shaft first and give it to your rebuilder. This way there will be no need to tear apart your transmission again to install it later.
 

FLINT

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Western VA mtns.
Won't most trucks already have the 208 t-case? would it be easier to use the donor t-case that is already mated to the tranny? I'm assuming that I would be getting the tranny from a diesel parts truck which really shouldn't be to hard to find. there was one if the local paper two weeks ago.
 

Iceman3005

Active member
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Location
Holt, MI
an np208 that was behind a turbo 350 will bolt right up too the 700r4 just make sure you get the adapter with it. They still make the tv cable just bought it from auto zoned, and the rod the connects too the cable I just bought from the chevy dealer, they don't make the bracket anymore though. as far as the torque converter lock up there are several kits out there so it will work without the computer, just look on ebay.
 

southdave

Active member
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Location
ripley, oh/TDY Lordstown,Oh
Won't most trucks already have the 208 t-case? would it be easier to use the donor t-case that is already mated to the tranny? I'm assuming that I would be getting the tranny from a diesel parts truck which really shouldn't be to hard to find. there was one if the local paper two weeks ago.
You are correct sir... A 208 is 208 the shaft swap is unnessary expense for most for us if you need a heavier combo it would be for a 205. FYI get the tie bar!!! I cant seem to find one.. I'll have to make one I guess
 

Chief_919

Well-known member
2,050
100
63
Location
Western NC
Well, I am about 400 miles into my 700R4 swap, and all I can say is that it is the best thing I have ever done to my truck.

The lower first gear is very noticable when you start, feels like a lot more power. I can cruise at 65 and not go deaf!

I had a local shop do the swap. I got a fresh rebuilt 700R4, with aftermarket clutch packs to make it stronger for towing, they swapped the transfer case for me, provided a new flexplate, and provided all the parts to do the install (including fabricating a TV cable bracket) and I was out the door for $1625. We went with a non lockup converter, that raises my RPM's in OD a little but also gives me a bit more torque in OD, and here in the mountains I like that. It also eliminated having to add any wiring.

Only issue I have is the speedo is reading 25% high- and they warned me before it would likely be off- so I need to look up the gears to fix that. But since I always use the readout on the GPS anyway, not a big deal.
 

Chief_919

Well-known member
2,050
100
63
Location
Western NC
This is my next major project as soon as my lift is done. Thanks for the review. Have you figured out your mileage yet? Also with the Torque Convertor locked up you will get much better fuel economy!:driver:
I can't really give a good estimate on the mileage yet since I have been hauling about 1k in the bed and pulling a trailer up and down the mountain, but I can tell you the needle goes down a lot slower....

I am headed to Bragg tomorrow, then Jackson, then home so that will be a good amount of highway time. It will be loaded with a trailer but that should give me a good idea.
 

armytruck63

Active member
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Location
Redlands, CA
Only issue I have is the speedo is reading 25% high- and they warned me before it would likely be off- so I need to look up the gears to fix that. But since I always use the readout on the GPS anyway, not a big deal.
A speedometer shop can make you an inline gear box that corrects the speedometer. I had to do this when I converted my Pinzgauer's speedometer from kilometers to miles.
 

Iceman3005

Active member
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97
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Location
Holt, MI
I'm in the process of doing my swap right now. Will start a new thread with pics soon. TCC lockup is a must, it keeps the torque converter about 100 degrees cooler in 4th gear, (no slip).
The wiring is very simple only takes 15 minutes to change.
 

Chief_919

Well-known member
2,050
100
63
Location
Western NC
I'm in the process of doing my swap right now. Will start a new thread with pics soon. TCC lockup is a must, it keeps the torque converter about 100 degrees cooler in 4th gear, (no slip).
The wiring is very simple only takes 15 minutes to change.
They built the transmission in mine and the torque converter knowing it would be a non-lockup, so heat won't be an issue they say. It involves a non-lockup valve and changes to the cooling circuit.

Now had it been built as a lockup and then left unlocked that would get hot quick.


Trans temp gauge is going in next week and I will know for sure.
 
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